ARM as a primary architecture

Jon Masters jcm at
Wed Mar 28 23:27:30 UTC 2012

On 03/23/2012 08:18 PM, Kevin Kofler wrote:
> DJ Delorie wrote:
>>> always with the caveat that you can't just use "make -j 288" on them.
>> Why not?  Multi-CPU machines is very old technology.
> Ask the people who designed those machines.
> (My guess: memory and bus bandwidth. There's a limit to how many cores you 
> can put on a shared-memory, shared-devices machine.)

This is true. In the case of Cortex-A9 there are limits to how many
fully coherent cores exist within a given CPU "cluster" (on-chip). There
are also limits to coherency domains that generally mean you can't do
multi-socket coherency on practical 32-bit implementations. In the case
of 64-bit, one of the vendors at least has publicly announced an
intention to support fully coherent multi-socket domains. But in the
interim, we're going to have typically 4 core systems, and many of them.


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